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authorBartosz Golaszewski <bgolaszewski@baylibre.com>2019-03-22 18:27:12 +0100
committerBartosz Golaszewski <bgolaszewski@baylibre.com>2019-03-27 09:56:01 +0100
commit2583303debb7acc77295b77901916d08a4c743c2 (patch)
treedcafb0c6f74db205d336c9b9c10e0ff37c687666 /drivers/gpio/gpio-mockup.c
parentfa59dd234c9a237e590a5f6db530d7f7ee88e5e8 (diff)
downloadlinux-2583303debb7acc77295b77901916d08a4c743c2.tar.bz2
gpio: mockup: fix debugfs read
The debugfs read callback must advance ppos or users using read() on the file descriptor will never get the EOL. This wasn't spotted before as I was using busybox cat for testing which uses sendfile() internally and only noticed it now when switched to cat from coreutils. Fixes: 2a9e27408e12 ("gpio: mockup: rework debugfs interface") Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Diffstat (limited to 'drivers/gpio/gpio-mockup.c')
-rw-r--r--drivers/gpio/gpio-mockup.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 154d959e8993..74ba8b1d71d8 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -204,8 +204,9 @@ static ssize_t gpio_mockup_debugfs_read(struct file *file,
struct gpio_mockup_chip *chip;
struct seq_file *sfile;
struct gpio_chip *gc;
+ int val, rv, cnt;
char buf[3];
- int val, rv;
+
if (*ppos != 0)
return 0;
@@ -216,13 +217,14 @@ static ssize_t gpio_mockup_debugfs_read(struct file *file,
gc = &chip->gc;
val = gpio_mockup_get(gc, priv->offset);
- snprintf(buf, sizeof(buf), "%d\n", val);
+ cnt = snprintf(buf, sizeof(buf), "%d\n", val);
- rv = copy_to_user(usr_buf, buf, sizeof(buf));
+ rv = copy_to_user(usr_buf, buf, cnt);
if (rv)
return rv;
- return sizeof(buf) - 1;
+ *ppos += cnt;
+ return cnt;
}
static ssize_t gpio_mockup_debugfs_write(struct file *file,